Vibration dampening grip cover for the handle of an implement

ABSTRACT

A vibration absorbing padding including a padding body formed by a multi-layer material. The material preferably includes a first elastomeric layer of vibration absorbing material which is substantially free of voids therein. A second elastomeric layer includes an aramid material therein and is disposed on the first elastomeric layer. The amramid material distributes vibration to facilitate vibration dampening. A third elastomeric layer is disposed on the second elastomeric layer.

CROSS REFERENCE TO RELATED APPLICATION

This application is a divisional of and claims priority to U.S. patentapplication Ser. No. 09/939,319, filed on Aug. 27, 2001, now U.S. Pat.No. 6,652,398 which is hereby incorporated by reference herein as iffully set forth in its entirety.

BACKGROUND OF THE INVENTION

U.S. Pat. Nos. 5,653,643 and 5,944,617 disclose vibration absorbingmaterial which is particularly useful when applied to the gripping areaof the handle of some type of implement such as a golf club or varioustypes of other athletic equipment or tools. The material described inthose patents is of single layer form having certain characteristicswith regard to its friction, vibration dampening and hardness features.It would be desirable if variations could be provided for such materialwhich would enhance the characteristics of the material withoutsignificantly resulting in a material which is of impractical thickness.Ideally, such material should provide a sting free grip which could bereadily adapted to the handle of various types of implements such asathletic equipment, tools and handlebars.

SUMMARY OF THE INVENTION

An object of this invention is to provide a variation of the techniquesdescribed in U.S. Pat. Nos. 5,653,643 and 5,944,617.

In accordance with one practice of this invention a molded sleeveincludes sleeve is utilized for fitting over the handle of an implement.The sleeve is open at one end to facilitate the sleeve fitting aroundthe handle. The other end of the outwardly extending peripheral knobwhich acts as a stop to minimize any tendency of the user's hand to slipfrom the handle. By making the knob of vibration dampening material, theknob also cooperates in achieving a sting free grip. The sleeve itselfcould be made of single layer form from the type of material shown anddescribed in U.S. Pat. Nos. 5,653,643 and 5,944,617. Alternatively, thesleeve could be a multilayer laminate having an inner layer of such typeof material of the aforenoted patents and an outer layer of tackymaterial which could be the same as or different from the inner layer.

In a preferred practice of the invention there is at least oneintermediate layer which is preferably made of a force dissipating orstiffening material such as aramid fibers.

The invention may also be practiced where the sleeve or cover does notnecessarily include a knob and wherein the cover is a multilayerlaminate as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view of a baseball bat having a cover in theform of a sleeve on the handle area in accordance with this invention;

FIG. 2 is an enlarged fragmental cross-sectional view of the bat andsleeve shown in FIG. 1;

FIG. 3 is a schematic diagram showing the results in the application ofshock forces on a cover in accordance with this invention;

FIG. 4 is a view similar to FIG. 2 showing an alternative sleeve mountedon a different implement;

FIG. 5 is a view similar to FIGS. 2 and 4 showing still yet another formof sleeve in accordance with this invention; FIG. 6 is a cross-sectionallongitudinal view showing an alternative cover in accordance with thisinvention mounted on a further type of implement;

FIG. 6 is a cross-sectional longitudinal view showing an alternativecover in accordance with this invention mounted on a further type ofimplement;

FIG. 7 is a cross-sectional end view of yet another cover in accordancewith this invention;

FIG. 8 is an elevational view of a hammer incorporating an abrasivedampening handle in accordance with this invention;

FIG. 9 is an elevational view showing a portion of a handlebarincorporating a vibration dampening cover in accordance with thisinvention;

FIG. 10 is a view similar to FIG. 9 of yet another practice of thisinvention; and

FIGS. 11-14 are plan views of various forms of the intermediate forcedissipating layer which is used in certain practices of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is directed to a cover for the handle of animplement. The cover is made of a vibration dampening or vibrationabsorbing material which may include as one layer the type of materialdisclosed in U.S. Pat. Nos. 5,653,643 and 5,944,617. All of the detailsof those patents are fully incorporated herein not only with regard tothe materials, but also with regard to the devices to which the materialmay be applied, as well as other disclosures in those patents.

FIGS. 1-2 illustrate one practice of this invention. As shown therein acover in the form of a sleeve 10 is mounted on the handle or lowerportion 18 of a baseball bat 10. Sleeve 10 is premolded so that it canbe fit onto the handle portion of the bat 12 in a quick and convenientmanner. This can be accomplished by having the sleeve 10 made of astretchable or resilient material so that its upper end 14 would bepulled open and could be stretched to fit over the knob 17 of the bat12. Alternatively, or in addition, sleeve 10 may be provided with alongitudinal slit 16 to permit the sleeve to be pulled at leastpartially open and thereby facilitate snapping the sleeve 10 over thehandle 18 of the bat 12. The sleeve would remain mounted in place due tothe tacky nature of the sleeve material and/or by the application of asuitable adhesive on the inner surface of the sleeve and/or on the outersurface of handle 18.

A characterizing feature of sleeve 10, as illustrated in FIGS. 1-2, isthat the lower end of the sleeve includes an outwardly extendingperipheral knob 20. Knob 20 could be a separate cap snapped onto orsecured in any other manner to the main portion of sleeve 10.Alternatively, knob 20 could be integral with and molded as part of thesleeve 10.

In a broad practice of this invention, sleeve 10 is of a single layermade from the type of material described in U.S. Pat. Nos. 5,653,643 and5,944,617. Such material is a vibration dampening material, an examplebeing a silicone gel such as used for caulking purposes. The materialwould have the appropriate hardness and vibration dampeningcharacteristics. The outer surface of the material would be tacky havinghigh friction characteristics.

Alternatively, the sleeve 10 could be formed from a two layer laminatewhere the vibration absorbing material forms the inner layer disposedagainst the handle, with a separate tacky outer layer made from anysuitable high friction material such as a thermoplastic material withpolyurethane being one example. Thus, the two layer laminate would havean inner elastomer layer which is characterized by its vibrationdampening ability, while the main characteristic of the outer elastomerlayer is its tackiness to provide a suitable gripping surface that wouldresist the tendency for the user's hand to slide off the handle. Theprovision of the knob 20 also functions both as a stop member tominimize the tendency for the handle to slip from the user's hand and tocooperate in the vibration dampening affect.

FIG. 2 illustrates the preferred form of multilayer laminate whichincludes the inner vibration absorbing layer 22 and the outer tackygripping layer 24 with an intermediate layer 26 made of a stiffeningmaterial which dissipates force. If desired layer 26 could be innermostand layer 24 could be the intermediate layer. A preferred stiffeningmaterial would be aramid fibers which could be incorporated in thematerial in any suitable manner as later described with respect to FIGS.11-14.

FIG. 3 schematically shows what is believed to be the affect of theshock forces from vibration when the implement makes contact such asfrom the bat 12 striking a ball. FIG. 3 shows the force vectors inaccordance with a three layer laminate, such as illustrated in FIG. 2,wherein elastomeric layers 22,24 are made of a silicone material of thetype described in U.S. Pat. Nos. 5,653,643 and 6,944,617. Theintermediate layer 26 is an aramid layer made of Kevlar® fibers. Theinitial shock or vibration is shown by the lateral or transverse arrows28 on each side of the sleeve laminate 10. This causes the elastomericlayers 22,24 to be compressed along the arc 30. The inclusion of theintermediate layer 26 made from a force dissipating material spreads thevibration longitudinally as shown by the arrows 32. The linear spread ofthe vibration causes a rebound effect which totally dampens thevibration.

Laboratory tests were carried out at a prominent university to evaluatevarious grips mounted on baseball bats. In the testing, baseball batswith various grips were suspended from the ceiling by a thin thread;this achieves almost a free boundary condition that is needed todetermine the true characteristics of the bats. Two standard industrialaccelerometers were mounted on a specially fabricated sleeve roughly inpositions where the left hand and the right hand would grip the bat. Aknown force was delivered to the bat with a standard calibrated impacthammer at three positions, one corresponding to the sweet spot, theother two simulating “miss hits” located on the mid-point and shaft ofthe bat. The time history of the force as well as the accelerations wererouted through a signal conditioning device and were connected to a dataacquisition device. This was connected to a computer which was used tolog the data.

Two series of tests were conducted. In the first test, a control bat(with a standard rubber grip, WORTH Bat—model #C405) was compared toidentical bats with several “Sting-Free” grips representing practices ofthe invention. These “Sting-Free” grips were comprised of two layers ofpure silicone with various types of Kevlar® inserted between the twolayers of silicone. The types of Kevlar® used in this test werereferenced as follows: “005”, “645”, “120”, “909”. Also, a bat with justa thick layer of silicone but no Kevlar® was tested. With the exceptionof the thick silicone (which was deemed impractical because of theexcessive thickness), the “645” bat showed the best reduction invibration magnitudes.

The second series of tests were conducted using EASTON Bats (model #BK8)with the “645” Kevlar® in different combinations with silicone layers:The first bat tested was comprised of one bottom layer of silicone witha middle layer of the “645” Kevlar© and one top layer of siliconereferred to as “111”. The second bat test was comprised of two bottomlayers of silicone with a middle layer of Kevlar® and one top layer ofsilicone referred to as “211”. The third bat tested was comprised of onebottom layer of silicone with a middle layer of Kevlar© and two toplayers of silicone referred to as “112”. The “645” bat with the “111”configuration showed the best reduction in vibration magnitudes.

In order to quantify the effect of this vibration reduction, twocriteria were defined: (I) the time it takes for the vibration todissipate to an imperceptible value; and, (2) the magnitude of vibrationin the range of frequencies at which the human hand is most sensitive.

The sting-free grips reduced the vibration in the baseball bats by bothquantitative measures. In particular, the “645” Kevlar® in a “111”configuration was the best in vibration reduction. In the case of abaseball bat, the “645” reduced the bat's vibration in about ⅕ the timeit took the control rubber grip to do so. The reduction in peakmagnitude of vibration ranged from 60% to 80%, depending on the impactlocation and magnitude.

It was concluded that the “645” Kevlar® grip in a “111” combinationreduces the magnitude of sensible vibration by 80% that is induced in abaseball bat when a player hits a ball with it. This was found to betrue for a variety of impacts at different locations along the length ofthe bat. Hence, a person using the “Sting-Free” grips of the inventionwould clearly experience a considerable reduction in the sting effect(pain) when using the “Sting-free” grip than one would with a standardgrip.

In view of the above tests a particularly preferred practice of theinvention involves a multilayer laminate having an aramid such asKevlar®, sandwiched between layers of pure silicone. The above indicatedtests show dramatic results with this embodiment of the invention. Asalso indicated above, however, the laminate could comprise othercombinations of layers such as a plurality of bottom layers of siliconeor a plurality of top layers of silicone. other variations include arepetitive laminate assembly wherein a vibration dampening layer isinnermost with a force dissipating layer against the lower vibrationdampening layer and then with a second vibration dampening layer overthe force dissipating layer followed by a second force dissipatinglayer, etc. with the final laminate layer being a gripping layer whichcould also be made of vibration dampening material. Among theconsiderations in determining which laminate should be used would be thethickness limitations and the desired vibration dampening properties.

The various layers could have different relative thicknesses.Preferably, the vibration dampening layer, such as layer 22, would bethe thickest of the layers. The outermost gripping layer, however, couldbe of the same thickness as the vibration dampening layer, such as layer24 shown in FIG. 2 or could be a thinner layer since the main functionof the outer layer is to provide sufficient friction to assure a firmgripping action. A particularly advantageous feature of the inventionwhere a force dissipating stiffening layer is used is that the forcedissipating layer could be very thin and still achieve its intendedresults. Thus, the force dissipating layer would preferably be thethinnest of the layers, although it might be of generally the samethickness as the outer gripping layer. If desired the laminate couldalso include a plurality of vibration dampening layers (such as thinlayers of gel material) and/or a plurality of stiffening forcedissipating layers. Where such plural layers are used, the variouslayers could differ in the thickness from each other.

FIGS. 1-2 show the use of the invention where the sleeve 10 is mountedover a baseball bat 12 having a knob 17. The same general type structurecould also be used where the implement does not have a knob similar to abaseball bat knob. FIG. 4, for example, illustrates a variation of theinvention wherein the sleeve 10A would be mounted on the handle 18A ofan implement that does not terminate in any knob. Such implement couldbe various types of athletic equipment, tools, etc. The sleeve 10A,however, would still have a knob 20A which would include an outergripping layer 24A, an intermediate force dissipating layer 26A and aninner vibration dampening layer 22A. In the embodiment shown in FIG. 4,the handle 18A extends into the knob 20A. Thus, the inner layer 22Awould have an accommodating recess 34 for receiving the handle 18A. Theinner layer 22A would also be of greater thickness in the knob area asillustrated.

FIG. 5 shows a variation where the sleeve 10B fits over handle 18Bwithout the handle 18B penetrating the knob 20B. As illustrated, theouter gripping layer 24B would be of uniform thickness both in thegripping area and in the knob. Similarly, the intermediate forcedissipating layer 26B would also be of uniform thickness. The innershock absorbing layer 22B, however, would completely occupy the portionof the knob inwardly of the force dissipating layer 26B since the handle18B terminates short of the knob 20B.

FIG. 6 shows a variation of the invention where the gripping cover 36does not include a knob. As shown therein, the gripping cover would bemounted over the gripping area of a handle 38 in any suitable manner andwould be held in place either by a previously applied adhesive or due tothe tacky nature of the innermost vibration dampening layer 40 or due toresilient characteristics of the cover 36. Additionally, the cover mightbe formed directly on the handle 38. FIG. 8, for example, shows a cover36B which is applied in the form of tape.

As shown in FIG. 6 the cover 36 includes one of the laminate variationswhere a force dissipating layer 42 is provided over the inner vibrationdampening layer 40 with a second vibration dampening layer 44 appliedover force dissipating layer 42 and with a final thin gripping layer 46as the outermost layer. As illustrated, the two vibration dampeninglayers 40 and 44 are the thickest layers and may be of the same ordiffering thickness from each other. The force dissipating layer 42 andouter gripping layer 44 are significantly thinner.

FIG. 7 shows a cover 36A mounted over a hollow handle 38A which is ofnon-circular cross-section. Handle 38A may, for example, have theoctagonal shape of a tennis racquet.

FIG. 8 shows a further cover 36B mounted over the handle portion of toolsuch as hammer 48. As illustrated, the cover 36B is applied in tape formand would conform to the shape of the handle portion of hammer 48. Otherforms of covers could also be applied rather than using a tape.Similarly, the tape could be used as a means for applying a cover toother types of implements.

FIG. 9 illustrates a cover 36C mounted over the end of a handlebar, suchas the handlebar of various types of cycles or any other device having ahandlebar including steering wheels for vehicles and the like. FIG. 9also illustrates a variation where the cover 36C has an outer contourwith finger receiving recesses 52. Such recesses could also be utilizedfor covers of other types of implements.

FIG. 10 illustrates a variation of the invention where the cover 36D ismounted to the handle portion of an implement 54 with the extreme end 56of the implement being bare. This illustration is to show that theinvention is intended to provide a vibration dampening gripping coverfor the handle of an implement and that the cover need not extend beyondthe gripping area. Thus, there could be portions of the implement onboth ends of the handle without having the cover applied to thoseportions.

In a preferred practice of the invention, as previously discussed, aforce dissipating stiffening layer is provided as an intermediate layerof a multilayer laminate where there is at least one inner layer ofvibration dampening material and an outer layer of gripping materialwith the possibility of additional layers of vibration dampeningmaterial and force dissipating layers of various thickness. As noted theforce dissipating layer could be innermost. The invention may also bepracticed where the laminate includes one or more layers in addition tothe gripping layer and the stiffening layer and the vibration dampeninglayer. Such additional layer(s) could be incorporated at any location inthe laminate, depending on its intended function (e.g., an adhesivelayer, a cushioning layer, etc.).

The force dissipating layer could be incorporated in the laminate invarious manners. FIG. 11, for example, illustrates a force dissipatingstiffening layer 58 in the form of a generally imperforate sheet. FIG.12 illustrates a force dissipating layer 60 in the form of an open meshsheet. This is a particularly advantageous manner of forming the forcedissipating layer where it is made of Kevlar® fibers. FIG. 13illustrates a variation where the force dissipating layer 62 is formedfrom a plurality of individual strips of material 64 which are parallelto each other and generally identical to each other in length andthickness as well as spacing. FIG. 14 shows a variation where the forcedissipating layer 66 is made of individual strips 68 of different sizesand which could be disposed in a more random fashion regarding theirorientation. Although all of the strips 68 are illustrated in FIG. 14 asbeing parallel, non-parallel arrangements could also be used.

The vibration dampening grip cover of this invention could be used for awide number of implements. Examples of such implements include athleticequipment, hand tools and handlebars. For example, such athleticequipment includes bats, racquets, sticks, javelins, etc. Examples oftools include hammers, screwdrivers, shovels, rakes, brooms, wrenches,pliers, knives, handguns, air hammers, etc. Examples of handlebarsinclude motorcycles, bicycles and various types of steering wheels.

A preferred practice of this invention is to incorporate a forcedissipating layer, particularly an aramid, such as Kevlar® fiber, into acomposite with at least two elastomers. One elastomer layer wouldfunction as a vibration dampening material and the other outer elastomerlayer which would function as a gripping layer. The outer elastomerlayer could also be a vibration dampening material. Preferably, theouter layer completely covers the composite.

There are an almost infinite number of possible uses for the compositeof laminate of this invention. In accordance with the various uses theelastomer layers may have different degrees of hardness, coefficient offriction and dampening of vibration. Similarly, the thicknesses of thevarious layers could also vary in accordance with the intended use.Examples of ranges of hardness for the inner vibration dampening layerand the outer gripping layer (which may also be a vibration absorbinglayer) are 5-70 Durometer Shore A. One of the layers may have a range of5-20 Durometer Shore A and the other a range of 30-70 Durometer Shore Afor either of these layers. The vibration dampening layer could have ahardness of less than 5, and could even be a 000 Durometer reading. Thevibration dampening material could be a gel, such as a silicone gel or agel of any other suitable material. The coefficient of friction asdetermined by conventional measuring techniques for the tacky andnon-porous gripping layer is preferably at least 0.5 and may be in therange of 0.6-1.5. A more preferred range is 0.7-1.2 with a still morepreferred range being about 0.8-1. The outer gripping layer, when alsoused as a vibration dampening layer, could have the same thickness asthe inner layer. When used solely as a gripping layer the thicknesscould be generally the same as the intermediate layer, which might beabout {fraction (1/20)} to ¼ of the thickness of the vibration dampeninglayer.

The grip cover of this invention could be used with various implementsas discussed above. Thus, the handle portion of the implement could beof cylindrical shape with a uniform diameter and smooth outer surfacesuch as the golf club handle 38 shown in FIG. 4. Alternatively, thehandle could taper such as the bat handle shown in FIGS. 1-2. Otherillustrated geometric shapes include the octagonal tennis racquet handle38A shown in FIG. 7 or a generally oval type handle such as the hammer48 shown in FIG. 8. The invention is not limited to any particulargeometric shape. In addition, the implement could have an irregularshape such as a handle bar with finger receiving depressions as shown inFIG. 9. Where the outer surface of the implement handle is of non-smoothconfiguration the inner layer of the cover could press against andgenerally conform to the outer surface of the handle and the outermostgripping layer of the cover could include its own finger receivingdepressions. Alternatively, the cover may be of uniform thickness of ashape conforming to the irregularities in the outer surface of thehandle.

Other variations and uses will be readily apparent to those of ordinaryskill in the art in view of the above teachings, examples andsuggestions.

1. A vibration absorbing padding, comprising: a padding body formed by amulti-layer material comprising: a first elastomeric layer of vibrationabsorbing material which is substantially free of voids therein; secondelastomeric layer which includes an aramid material therein and that isdisposed on the first elastomeric layer, wherein the aramid materialdistributes vibration to facilitate vibration dampening, wherein thearamid material forms an imperforate sheet disposed within the secondelastomeric layer; and a third elastomeric layer disposed on the secondelastomeric layer.
 2. A vibration absorbing padding, comprising: apadding body formed by a multi-layer material comprising: a firstelastomeric layer of vibration absorbing material which is substantiallyfree of voids therein; a second elastomeric layer which includes anararnid material therein and that is disposed on the first elastomericlayer, wherein the aramid material distributes vibration to facilitatevibration dampening, wherein the aramid material forms a plurality ofindividual strips that are substantially parallel to each other; and athird elastomeric layer disposed on the second elastomeric layer.
 3. Thepadding of claim 2, wherein the plurality of individual strips aregenerally equally sized.
 4. A vibration absorbing padding, comprising: apadding body formed by a multi-layer material comprising: a firstelastomeric layer of vibration absorbing material which is substantiallyfree of voids therein; a second elastomeric layer which includes anaramid material therein and that is disposed on the first elastomericlayer, wherein the aramid material distributes vibration to facilitatevibration dampening, wherein the aramid material forms a plurality ofindividual strips of different sizes that are substantially parallel toeach other; and a third elastomeric layer disposed on the secondelastomeric layer.
 5. A vibration absorbing padding, comprising: a firstelastomeric layer adapted to absorb vibration, the first elastomericlayer being substantially free of voids therein; a second elastomericlayer which includes an aramid material therein and that is disposed onthe first elastorneric layer, the aramid material comprising a pluralityof individual strips of aramid of different sizes, wherein the aramidmaterial distributes vibration to facilitate vibration dampening, thesecond elastomeric layer being substantially free of voids therein; athird elastomeric layer that is disposed on the second elastomericlayer, the third elastomeric layer being substantially free of voids. 6.A vibration absorbing padding, comprising: an first layer adapted toabsorb vibration and being formed by an elastomer that is substantiallyfree of voids therein; a second layer which includes an aramid materialtherein and that is disposed on the first layer, the aramid materialcomprising a plurality of individual strips of aramid of generally equalsizes, wherein the aramid material distributes vibration to facilitatevibration dampening, the second layer being substantially free of voidstherein, the plurality of individual aramid strips being generallyparallel to each other; and a third layer formed by an elastomer that issubstantially free of voids.